The present invention relates to a gate valve which may be used to control the flow of fluid through various components of a flow completion system, such as a tubing hanger. More particularly, the invention relates to such a gate valve which is remotely operable and which is oriented generally longitudinally in the component and therefore occupies a minimum of the radial cross sectional area of the component.
The need to remotely and reliably control the flow of fluid through components having relatively small radial cross sectional areas is particularly strong in the field of flow completion systems for producing oil or gas from a subsea well. A typical horizontal-type flow completion system comprises a wellhead housing which is installed at the upper end of a well bore, a tubing spool which is connected to the top of the wellhead housing and which includes a central bore extending axially therethrough, and a tubing hanger which is suspended in the central bore and which supports at least one tubing string that extends into the well bore and defines a tubing annulus surrounding the tubing string. The tubing hanger is usually an annular component which includes at least one longitudinal production bore connected to the tubing string, a lateral production passageway that extends between the production bore and a production outlet in the tubing spool, and one or more service and control conduits for communicating control signals or fluids from external service and control lines to corresponding devices or positions located in or below the tubing hanger. In addition, the tubing hanger may include a longitudinal annulus bore for connecting the tubing annulus with the portion of the central bore located above the tubing hanger.
In operation of the flow completion system, flow through the annulus bore and the service and control conduits must be carefully controlled to ensure that well fluid does not escape into the environment. For example, during installation and workover of the flow completion system, the annulus bore must typically remain closed until a blowout preventer (xe2x80x9cBOPxe2x80x9d) is installed above the tubing hanger, at which point the tubing hanger may be opened to allow for circulation of fluid between the production bore and the tubing annulus. In the prior art, a wireline plug is typically used to close the annulus bore. However, each installation or removal of the plug requires a special trip from a surface vessel. Moreover, although several versions of remotely operable valves for controlling flow through the annulus bore have been patented, these valves have for the most part been impractical to implement due to the limited radial cross sectional area that is available in the tubing hanger for such valves.
Therefore, a need exists for a remotely operable valve which can reliably control the flow of fluid through a flow completion system component but which occupies a minimum radial cross sectional area of the component.
In accordance with the present invention, these and other disadvantages in the prior art are overcome by providing a closure member for a component having an elongated body and a flow passage extending generally longitudinally through the body, the flow passage including a generally lateral first branch connected to a generally longitudinal second branch. The closure member comprises a gate which is moveable generally longitudinally across the first branch between an open position in which a hole in the gate is aligned with the first branch and a closed position in which the hole is offset from the first branch, a conduit which extends through the body from the gate, an actuating mechanism positioned in the conduit for moving the gate from the closed position to the open position, and a return biasing mechanism for moving the gate from the open position to the closed position, wherein the conduit extends generally longitudinally through the body. In a preferred embodiment of the invention the actuating mechanism comprises a piston which is connected to the gate and which sealingly engages the conduit, and means for conveying hydraulic pressure to a first portion of the conduit which communicates with the piston.
Thus, it may be seen that the components of the closure member which move the gate are aligned generally longitudinally relative to the gate. In this manner, the closure member occupies a minimum amount of the lateral cross sectional area of the component compared to prior art closure members. In addition, since hydraulic pressure is used to actuate the gate, the closure member may be operated remotely.
In one embodiment of the present invention, the closure member is adapted for use in a tubing hanger which is suspended in a tubing spool and which comprises an elongated body having an annulus bore that extends generally axially therethrough, the annulus bore comprising a generally lateral first branch connected to a generally axial second branch. Accordingly, the closure member comprises a gate which is moveable generally axially across the first branch between an open position in which a hole in the gate is aligned with the first branch and a closed position in which the hole is offset from the first branch, a conduit which extends generally axially through the body from the gate, an actuating mechanism positioned in the conduit for moving the gate from the closed position to the open position, and return biasing mechanism for moving the gate from the open position to the closed position. In a preferred embodiment of the invention, the actuating mechanism comprises a piston which is connected to the gate and which sealingly engages the conduit, and means for conveying hydraulic pressure to a first portion of the conduit which communicates with the piston. Furthermore, the tubing hanger ideally comprises first and second annular seals positioned between the body and the tubing spool, and the closure member further comprises a gate cavity in which the gate is at least partially positioned and which extends into the body from between the first and second seals, wherein pressure within the gate cavity is contained by the first and second seals.
Therefore it may be seen that the closure member of the present invention permits flow through the tubing hanger annulus bore to be reliably controlled from a remote location without the use of wireline plugs. Furthermore, since the gate and its actuating mechanism are oriented generally axially within the tubing hanger, the closure member occupies a minimum radial cross-sectional area of the tubing hanger.
These and other objects and advantages of the present invention will be made apparent from the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers are used to denote similar components in the various embodiments.